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Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 7 The Nervous SystemPage 200-215 (neurons, neuroglia, and impulses) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Nervous System • The master controlling and communicating system of the body • Uses electrical impulses to signal and communicate • Impulses are rapid and specific http://www.scienceclarified.com/Mu-Oi/Nervous-System.html Structures of nervous system Central Nervous System (CNS) Peripheral Nervous System (PNS) organs- organs- • Brain • Peripheral nerves • Spinal cord • Sense organs Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.3a Functions of the Nervous System • Sensory/Afferent: (PNS) • Uses sensory receptors to monitor internal & external changes/stimuli (input) • Integration: (CNS) • Processes and interprets and makes decisions about what should be done (interprets) • Motor/Efferent: (PNS) • Is the response; an activated viscera, muscle or gland (motor output or response) • Involuntary (autonomic) and Voluntary (somatic) Functions of nervous system PNS Affarent/ CNS PNS /Motor Receptor Figure 7.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.3a Functions of the Nervous System Integration Sensory input Motor output Figure 7.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.4 Anatomy of Nervous Tissue: Support Cells in CNS •called Neuroglia (page 205) •support, insulate, protect neurons, dispose of debris, circulate fluids astrocyte Figure 7.3: Types of Neuroglia oligodendrocyte microglial cell Ependymal cell Slide 7.7b Anatomy of Nervous Tissue: Support Cells in PNS called Schwann Cells and Satellite Cells Schwann cells form myelin sheath around nerve fiber of the PNS (insulate) Satellite Cells protect and cushion Figure 7.3e Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.7b Anatomy of Nervous Tissue: Structure of Neurons Neurons/Nerve Cells Highly specialized to transmit messages (impulses) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.8 Anatomy of Nervous Tissue: Structures of Neurons • Cell body: metabolic center, nissl substance, nucleus • Dendrite: slender processes, convey incoming messages to cell body, vary in length Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.8 Neuron Anatomy • Nissl bodiesrough ER Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.9a Neuron Anatomy Axon: conduct impulse away from cell body Myelin Sheath: insulation Axon Terminal Axon Terminals: branching ends of an axon Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.10 Neuron Anatomy Synaptic end bulbs: swollen end of axon, contain synaptic vesicles Axon terminal Synaptic end bulbs Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.10 Neuron Anatomy • synaptic vesicles: structure containing neurotransmitters Neurotransmitter: chemical messenger released when impulse reaches the synaptic vesicle, carries impulse across synaptic gap synaptic neurotransmitters Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.10 Synaptic End Bulb Neuron Anatomy Neurotransmitters: chemical messengers released from synaptic vesicles Carry impulse to next neuron or to the effector Figure 7.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.10 Neuron Structural Classification - All motor & association neuron, multiple processes - Only in special sense organs, 2 processes Figure 7.8a - In PNS ganglia, Short and divides immediately, single process Slide 7.16a Neuron Functional Classification Figure 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.15 Physiology of Neurons Irritability: ability to respond to stimuli Conductivity: ability to transmit an electrical impulse Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.17 Neuron Physiology: Transmission of a Nerve Impulse Figure 7.9a–c a. Polarization = Resting potential - lots of Na+ with some negative ions outside, and fewer K+ and lots of negative ions on the inside - overall negative charge is greater on the inside of the neuron - neuron is inactive Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings (b) Slide 7.18 Neuron Physiology: Transmission of a Nerve Impulse Figure 7.9a–c b. Depolarization = Action Potential – Na+ moves inward - The inside becomes less negative and more positive - causes transmission of an impulse (b) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.18 Transmission of a nerve impulse C. Repolarizationrestored resting state - K+ moves out, Na+ still inside (b) - this outflow of positive ions restores the electrical conditions of the membrane - but the neuron needs to be reset to its polarized state (c) Slide 7.19 Transmission of a nerve impulse D. Na+/K+ pump- restores polarized state - another impulse cannot be transmitted until Na+ and K+ are moved back to their original positions - this is by active transport, requires ATP Slide 7.19 All or none response Either all of neuron sends impulse, or none of it does Figure 7.9c–e Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.20 Transmission of Nerve Impulse http://www.britannica.com/EBchecked/topic/409665/nervoussystem/75842/Transmission-at-the-synapse(click on top video on left side of screen) http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_imp ulse.html http://video.google.com/videoplay?docid=6890770586678681705&ei=KIX1Ss_OFZLSqQL1zJGpAw&hl=en http://outreach.mcb.harvard.edu/animations/synaptic.swf Synapse synaptic end bulbs cell body dendrites Presynaptic neuron axon terminals Synaptic cleft (gap) Postsynaptic neuron Slide 7.22 Synapse (up close) neurotransmitter receptor sites Postsynaptic neuron Gap or Presynaptic axon Synaptic end bulbs Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.22 Synapse (up close) Figure 7.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.22 Synapses & Synaptic transmission Stimulus causes electrical impulse AKA action potential (via Na+ and K+) in neuron Impulse travels in presynaptic neuron Dendrites Cell body Axon, axon terminal, & synaptic end bulbs Synaptic vesicles Neurotransmitters- chemical impulse released Synaptic gap Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.21 Synapses & Synaptic transmission • In postsynaptic neuron Neurotransmitter receptor sites on dendrites receive new stimulus Stimulus causes electrical impulse again AKA action potential (via Na+ and K+) Impulse travels again from Dendrites Cell body Axon, axon terminals, synaptic end bulbs, Etc. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.21 The Reflex Arc •Reflex – rapid, predictable, and involuntary responses to stimuli •Simplest reflex arc has 5 components or interneuron Reflex arc Figure 7.11a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.23 Reflex Arc Figure 7.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 7.15 Simple Reflex Arc Knee jerk reflex Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Withdrawal reflex Figure 7.11b, c Slide 7.24 Factors that Affects Synaptic Transmission Emotional state- excited, sad, etc Physical state- exercise, sleep, etc Environmental factors- drugs, alcohol, etc Number of synapses Slide 7.22 Effects of Drugs on Synaptic Transmission Stimulants Depressants Cocaine Marijuana Crack Alcohol Ecstasy Opium Methamphetamine Barbiturates Amphetamine Antipsychotics Caffeine Anticonvulsants Nicotine Opiates Energy drinks Nitrous oxide Slide 7.22 Effects of Drugs on Synaptic Transmission http://teens.drugabuse.gov/mom/tg_effects.asp# http://www.nida.nih.gov http://www.drugabuse.gov/DrugPages/DrugsofAbuse.html Slide 7.22